#!/usr/bin/perl

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# Authors: Naveen Sastry
# Date:    11/11/02
#
#
# Script to manage the tinysec keyfile


# default keyfile and default key name (\w+ matches first valid key)
$KEYFILE=".keyfile";
$KEYNAME="\\w+";

# if no keyfile is found, we'll need to create it and populate it with data
# from /dev/random. This function returns the text taht should go into the 
# new keyfile. We store the key in a hex-form.
sub generateKey {
    print STDERR "Generating default TinySec Key...\n";
    
    $a = "\n# TinySec Keyfile. By default, the first key will be used.\n";
    $a = $a . "# You can import other keys by appending them to the file.\n";
    $a = $a . "\ndefault ";

    open RND, "</dev/urandom" or open "</dev/urandom" or 
        die("Couldn't open random file.");
    read RND, $r, 16;
    @chars = split //, $r;
    while (@chars) {
        $a = $a . sprintf("%02lX", (ord shift @chars));
    }
    return $a;
};

# Returns the binary version of the key (passed as the first arg)
sub recoverKey {
    $s = "";
    @chars = split /(..)/g, shift(@_);
    while (@chars) {
        $a = hex shift @chars;
        if ($a != 0 ) {
            $s = $s . chr ($a);
        }
    }
    return $s;
}

# Returns a text version of the key (passed as the key) suitable for use in c
# programs (ie returns "0x32,0xAB, ..." when given 32AB...)
sub splitKey {
    $s = "";
    $delim = "";
    @chars = split /(..)/g, shift(@_);
    while (@chars) {
        $a = shift @chars;
        if (! $a eq "" ) {
            $s = $s . $delim . "0x" . $a ;
            $delim = ",";
        }
    }
    return $s;
}

# prints the usage string and exits
sub usage {
    print "usage: TinySecKey [-kf keyfile] [-kn keyname]\n";
    print "       where \n";
    print "         [-kf keyfile] specifies an optional keyfile (default /home/$USER/.keyfile)\n";
    print "         [-kn keyname] specifies an optional keyname (default uses first) \n";
    exit 1;
}

# parse the args
while ($_ = $ARGV[0], /^-/) {
    shift;
    if (/^-kf/) { $KEYFILE = $ARGV[0]; shift; next;  }
    if (/^-kn/) { $KEYNAME = $ARGV[0] ; shift; next;  }
    usage();
}

# open the keyfile. if new, generate key data and reposition file pointer
open KEYFILE, '+<', $KEYFILE or
    (open KEYFILE, '+>', $KEYFILE and print KEYFILE generateKey() and
     seek KEYFILE, 0, 0) or
      die ("couldn't open file " . $KEYFILE);

# find the matching key and print.
while ( <KEYFILE> )  {
    if ($_ =~ /^$KEYNAME\s+([a-fA-F0-9]+)/) {
        $KEY = $1;
        last;
    }
}

print splitKey($KEY) . "\n";
